Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-18T13:46:47+00:00	DMARC	—	VALID	`51b2d23c2d9a…`
2026-08-18T13:46:47+00:00	SPF	—	VALID	`da46fce1b6ba…`